The present invention relates to a bead releasing and tire disassembling apparatus for disassembling tires from wheel-rims, particularly for use in tire disassembling machines.
Tire disassembling machines provided with tools for fitting, bead releasing and removing tires from their wheel-rims for vehicles with relatively large tired wheels, such as earthworks vehicles, have been known and used for quite a long time. Such tools are mounted e.g. at the end of an upright or “pole” rising from a carriage alternately displaceable in a direction parallel to the axis of rotation of the wheel-rim.
A tire disassembling machine for large tired vehicles generally comprises a base frame supporting two parallel overhanging arms suitable for being moved together, and away from, each other. One arm supports a suitable engagement and support means for the wheel-rim, e.g. a self-centring assembly, whereas the other arm, which is generally telescopic, supports a tool assembling/disassembling a tire onto or from its respective wheel-rim.
The said carriage supports a suitable tool used in the assembling or disassembling operation and can be displaced on guides close to the wheel or wheel-rim. For example, should the operator disassemble a tire from a wheel-rim, after deflating the tire, he displaces the carriage to move it in front of a wheel face and positions the bead releasing tool arranged at the top of the upright carried by the carriage, by adjusting the position of the carriage and the length of the upright according to the size of the wheel-rim.
The tool preferably comprises a disk or roller substantially conical in shape that is supported free to rotate on the upright or mandrel about an axis inclined with respect to the longitudinal axis of the mandrel and has a rounded larger peripheral edge designed to abut against the tire; as well as a curved removing tool arranged to be diametrically opposite and close to the disk, so that by rotating the tool through 180°, either the disk or the removing tool can be brought to its working position. However, the disk and the removing tool can also be mounted on two different uprights so that either of them can be brought to its working position.
Once said preliminary tool positioning operation has been completed, the operator positions the carriage in such a way that the edge of the conical disk thrusts the tire-bead which, after setting in rotation the self-centring device, and thus the wheel, is forced progressively to detach or to be released from the peripheral delimiting edge of the wheel-rim. The operator must then cause the carriage to be moved away from the wheel in order to allow the tool to rotate on itself through 180° to bring the removing tool to its working position. Each time the tool is rotated a locking means is released which normally comprises a pin transversely fitted in a through hole formed in the upright and in the base of the tool, and the pin is to be inserted in position. Once the tool has been rotated and locked in position, the carriage is to be once again moved close to the wheel to carry out the removal operation of the bead that has just been released.
The operator then effects bead releasing on the other side of the tire. In order to do so he must first release and move away the tool from the bead already released and removed from the first side, he then causes the upright to rotate about its vertical axis, in order to avoid to interfere with the wheel mounted on the self-centring device, and the carriage to effect a stroke sufficient to move the upright to the other side of the tire; the tool is then once again positioned by being rotated about vertical axis of the upright, in order to set the disk in its working position.
The bead on the second side or front of the tire is then released by acting in a way similar to that at the first front or side. The tool is rotated to position the removing tool so as to be facing towards the tire, whereby proceeding with the removal also of the second bead which has just been released; after which the carriage must be moved away from the wheel-rim.
All operations are carried out almost entirely manually and thus they are quite complicated, laborious, hence tiresome for the operator and require relatively long periods of time for being carried out correctly.
Additionally, since the tool comprises the bead releasing disk and the removing tool arranged diametrically opposite to each other, it is relatively cumbersome. Normally the overall dimensions of the tool exceeds 30% of the width of the wheel, and thus adequate space must be provided to carry out the operations of assembling and disassembling a tired wheel. This means that, in order to operate on wheels of relatively large dimensions (with a diameter up to 1.5 m), and bearing in mind that it is necessary to operate on both sides of a wheel, the tire assembling/disassembling machine must allow the tool-supporting carriage to effect strokes more than 2 m long.